Investigations will be performed to ascertain the role of brain catecholamines in the regulation of prolactin and gonadotropins during several different physiological, primarily reproductive, states in female rats. The effect of suckling on catecholamines will be determined in an effort to gain information on how neural impulses are translated to hypothalamic hormone and pituitary hormone release. Steroidal feedback will also be studied to determine whether it works through catecholamines. The effect of catecholamine synthesis-inhibitors or stimulants on pituitary hormones will be studied in parallel with studies on brain catecholamines. These drugs will be used to determine whether brain catecholamines are necessary for pituitary hormone secretion to occur in response to several different physiological stimuli.